The invention discloses a test method of the low voltage ride-through capability of a frequency converter based on a magnetic powder brake. The magnetic powder brake is employed as the simulation load of a coal feeder motor and a powder feeder motor, the loads carried by the coal feeder motor and the powder feeder motor are constant-torque loads, the output brake torque of the magnetic powder brake and field current are in a good linear relation and are irrelevant to the rotating speed or the slip, and the constant torque characteristic is represented in the specific field current. The magnetic powder brake is employed as the simulation load of the coal feeder motor and the powder feeder motor so that the low voltage ride-through capability of the frequency converter in the similar practical operation condition can be tested.